The present invention relates to locks and, in particular, to combination locks of the type which are installed on luggage, briefcases, metal lock boxes, etc.
Combination or permutation locks are typically employed in luggage and briefcases to secure together a pair of hinged sections, as is evident for example from the disclosures of Remington U.S. Pat. No. 4,308,731 issued Jan. 5, 1982 and Denerich U.S. Pat. No. 2,136,493 issued Nov. 15, 1938. In the Remington patent there is disclosed a lock wherein a lock unit on one of the hinged sections is arranged to lock and unlock a hasp on the other hinged section. The lock unit includes a slotted bolt which has a pair of mounting lugs seated in a pair of notches of a stationary frame. The notches define a fulcrum for the bolt, enabling a front latching end thereof to travel between latching and unlatching positions relative to the hasp. A series of rotary dials are disposed adjacent the bolt and project through slots in the bolt. The bolt is configured to engage cams which are drivingly connected to respective ones of the dials. Each cam is generally circular with an indented segment that can be flat or V-shaped. The bolt is in its unlocked position when the cams are arranged to engage the bolt with their indented segments, the bolt being spring-biased toward the cams. When any of the cams is displaced such that the circular periphery thereof engages the bolt, the bolt is swung about its rear anchoring end such that the front latching end is moved to a latching position against the spring bias. When the indented segment of the displaced cam(s) is returned to engagement with the bolt, the bolt again swings about its rear anchoring end under the spring bias such that the latching end moves to its unlocking position. One characteristic of such an arrangement is that when the latch is in a latching position, the hasp cannot be inserted into the latching assembly. That is, the latching end of the bolt unyieldably blocks the entrance to the latching mechanism.
In the afore-mentioned Denerich patent, a combination lock is disclosed wherein a lock unit receives and locks to a hasp even when in its locking mode. This is achieved by providing the latching end of the bolt with a cam face such that when the latch is closed and is engaged by the hasp, a force is imposed on the latch tending to swing the bolt to an auxiliary unlocking position in a direction opposite the normal unlocking direction of the bolt. The notches which receive the rear lugs are flared at their rear ends to accommodate a sufficient amount of pivotal movement of the lugs to enable the latch to be depressed to the auxiliary unlocking position by the hasp. After the hasp has passed over the latch, the bolt is returned to its locking position by a spring force. In such an arrangement, the notches define the sole fulcrum for movement of the bolt, similar to the afore-mentioned Remington patent. Since the extent of swinging movement of the bolt is greater in the Denerich patent due to the ability of the hasp to cam the latch in a direction opposite the usual unlocking direction, the height of the lock unit must be made large enough to accommodate such movement. Furthermore, since the bolt can be moved to an unlocking mode in a direction away from the dial axis and thus away from the exposed face plate through which the dials project, special care must be taken to ensure the security of the lock. That is, the design must be such that a slender tool cannot be inserted through the slots of the face plate (i.e., inserted between the dial and the face plate) sufficiently far to contact and push the bolt toward the auxiliary unlocking mode. It will further be appreciated that the design of the latch and hasp may be somewhat limited in the Denerich lock since such design must permit latching to occur when the latch approaches the hasp from two directions, i.e., toward and away from the dial axis.
It is, therefore, an object of the present invention to minimize or obviate shortcomings of the type previously discussed.
Another object of the invention is to provide an improved permutation lock.
A further object is to provide an improved permutation lock of the type incorporated within containers such as luggage, briefcases, metal boxes, etc., which enables a hasp to be locked even when the locking bolt is in a locking mode.
An additional object is to provide such a lock which is highly resistant to being "picked".
A further object is to provide such a lock which employs a closed hasp that presents a minimal risk of catching on clothing.